[build] Use sysroot for linux compilation with clang

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 63a51404ccebca29ebc3c176e9066c0e4faece81..4d700661d946e86a96d9d914273af352985d1539 100644
--- a/DEPS
+++ b/DEPS
@@ -190,6 +190,18 @@ hooks = [
     ],
   },
   {
+    # Downloads the current stable linux sysroot to build/linux/ if needed.
+    # This sysroot updates at about the same rate that the chrome build deps
+    # change.
+    'name': 'sysroot',
+    'pattern': '.',
+    'action': [
+        'python',
+        'v8/build/linux/sysroot_scripts/install-sysroot.py',
+        '--running-as-hook',
+    ],
+  },
+  {
     # Update the Windows toolchain if necessary.
     'name': 'win_toolchain',
     'pattern': '.',